Secure information distribution system utilizing information segment scrambling

ABSTRACT

A method and apparatus for securing and, optionally, distributing an information stream by divided the information stream into a collection of segments and compressing the segments, rearranging the order of the segments and encrypting the segments.

RELATED APPLICATIONS

This application claims the benefit of: U.S. Provisional Application No.60/097,264, filed Aug. 20, 1998, which is herein incorporated byreference in its entirety; and U.S. patent application Ser. No.09/182,933, now U.S. Pat. No. 7,457,415, filed Oct. 30, 1998, which isherein incorporated by reference in its entirety.

TECHNICAL FIELD

The invention relates to information distribution systems and, moreparticularly, the invention relates to methods and apparatus forsecuring information distributed within an information distributionsystem.

BACKGROUND OF THE DISCLOSURE

In several communications systems the data to be transmitted iscompressed so that the available bandwidth is used more efficiently. Forexample, the Moving Pictures Experts Group (MPEG) has promulgatedseveral standards relating to digital data delivery systems. The first,known as MPEG-1 refers to ISO/IEC standards 11172 and is incorporatedherein by reference. The second, known as MPEG-2, refers to ISO/IECstandards 13818 and is incorporated herein by reference. A compresseddigital video system is described in the Advanced Television SystemsCommittee (ATSC) digital television standard document A/53, and isincorporated herein by reference.

The above-referenced standards describe data processing and manipulationtechniques that are well suited to the compression and delivery ofvideo, audio and other information using fixed or variable lengthdigital communications systems. In particular, the above-referencedstandards, and other “MPEG-like” standards and techniques, compress,illustratively, video information using intra-frame coding techniques(such as run-length coding, Huffman coding and the like) and inter-framecoding techniques (such as forward and backward predictive coding,motion compensation and the like). Specifically, in the case of videoprocessing systems, MPEG and MPEG-like video processing systems arecharacterized by prediction-based compression encoding of video frameswith or without intra- and/or inter-frame motion compensation encoding.

Present electronic distribution systems typically do not strike anappropriate balance between flexibility and security for the purposes ofsome information distribution applications. For example, to enable theelectronic distribution of motion pictures (i.e., film) and otherentertainment video applications, it is necessary to dynamically process“trailers” (i.e., short previews of coming attractions”) on a locationby location basis, in addition to full length motion pictures. Withrespect to security, it is obviously necessary to incorporate a highlevel of security, ideally using a multi-layer security approach, suchthat the valuable intellectual property transmitted within the system isnot compromised.

Therefore, a need exists in the art for a secure and flexible method andapparatus for distributing information such as high-value motionpictures and other audio-video information, as well as other forms ofdata. Additionally, it is seen to be desirable to provide enhancedsecurity for various media, such as digital versatile disk (DVD) andother media.

SUMMARY OF THE INVENTION

A method and apparatus for securing and, optionally, distributing aninformation stream by divided the information stream into a collectionof segments and compressing the segments, rearranging the order of thesegments and encrypting the segments prior to, e.g., distributing theencrypted segments to one or more users within an informationdistribution system.

Specifically, in one embodiment of the invention, an input informationstream is divided into a collection of information segments, theindividual segments are then compressed and arranged in a non-standard(i.e., scrambled) manner to produce a scrambled collection ofinformation segments and an associated index table suitable for use inrearranging the collection of information segments into a standard(i.e., unscrambled) order. The scrambled collection of informationsegments and the associated index table are encrypted (using the same ordifferent encryption techniques) and distributed to one or moresubscribers (using the same or different distribution channels).Optionally, the scrambled collection of information segments isdistributed using a plurality of distribution channels (i.e., multipathdistribution) and/or at a plurality of different times (i.e., temporallystaggered distribution).

BRIEF DESCRIPTION OF THE DRAWINGS

The teachings of the present invention can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIG. 1 depicts an information distribution system 100 includingapparatus according to the invention;

FIG. 2 depicts a graphic representation of collection of informationsegments arranged in a non-standard (i.e., scrambled) order, and anindex table suitable for use in rearranging the collection ofinformation segments into a standard (i.e., unscrambled) order;

FIG. 3 depicts a flow routine of an information provider processingmethod according to the invention;

FIG. 4 depicts a flow diagram of a subscriber side method for processingan information stream according to the invention; and

FIG. 5 depicts a diagrammatic representation of the a layered securityenvironment enabled by the invention.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures.

DETAILED DESCRIPTION

The invention will be described within the context of an MPEG-likeinformation distribution system. It will be recognized by those skilledin the art that the invention is applicable to many types of informationdistribution systems. More specifically, the invention is ideally suitedto the protection and dissemination of information streams comprisingrelated sequenced of video and/or audio information, such as motionpictures, television and the like.

FIG. 1 depicts an information distribution system 100 includingapparatus according to the invention. Specifically, FIG. 1 depicts aninformation distribution system 100 comprising information providerequipment (105-140), information distribution channels (145A and 145B),and subscriber equipment (150-175). The information distribution system100 receives an input information stream IN′, illustratively anaudio-visual information stream such as a motion picture video streamand one or more associated audio or data streams. The input informationstream IN′ is processed by the provider equipment to produce a secureinformation stream that is coupled to the subscriber equipment via theinformation distribution channel(s). The secure information stream isreceived and processed by the subscriber equipment to produce an outputinformation stream OUT′ comprising the initial audio-visual informationstream IN′.

In one embodiment of the invention, a movie or other program iscompressed as a collection of self-contained MPEG-2 sequences, which maybe of non-uniform duration and size (number of bits). Fordistribution/storage, the sequences may be arbitrarily re-ordered and anindex table built that contains pointers to the storage locations ofsequences ordered in their correct presentation sequence. The reorderedsequences may be encrypted using standard encryption techniques. Theindex table may be separately encrypted using the same or differentencryption techniques. In addition, the index table may be distributedusing a different medium. For example, the encrypted and re-orderedsequences may be distributed on a DVD-ROM, while the encrypted indextable is downloaded to the receiver/decoder from an on-line server.Alternatively, a smart card could be used for the index table. Manyvariations are possible. At the receiver, the decrypted index table isused to control the random access readout of the encrypted sequencesfrom the storage medium. The video sequences are decrypted, decompressedand displayed in their proper order.

The index table approach not only achieves scrambling, but it alsoprovides an approach to flexibly accommodate trailers. The re-orderedvideo storage distributed to all locations would contain all trailers.The index table distributed to a particular location may indicate thedesired subset of trailers. In this manner, the index table andreordering approach provides both multi-level security andtrailer-handling flexibility.

It should be noted that within the scope of this invention, video andaudio may be separately segmented and independently re-ordered, withseparate index tables for each. Similarly, separate video components(e.g., R, G and B) may also be treated separately.

The information provider equipment within the information distributionsystem 100 of FIG. 1 comprises an optional pixel domain encoder module105, a segmentation module 110, a compression module 115, are-sequencing module 130, an information stream encryption module 135,an index table encryption module 140, and a plurality of optionalprovider storage modules 122, 124 and 126.

The optional pixel domain encoder 105 receives and processes the inputinformation stream IN′ according to one or more of a plurality of pixeldomain (or audio domain) processing techniques. These techniques will bedescribed in more detail below with respect to FIG. 3. As an example,the optional pixel domain encoder 105 may impart a digital watermarkingto video information within the received input information stream IN′such that copyright notices, source designation and other informationrelated to, e.g., the allowable use and/or ownership of the inputinformation stream IN′ may be inserted. The pixel domain encoder 105produces a pixel (or audio) domain encoded information stream IN that iscoupled to the segmentation module 110. It should be noted that withinthe context of this disclosure, the term “pixel domain” is used todenote more than the pixel or baseband video or image information. Theterm “pixel domain” is used to additionally denote audio and otherinformation (i.e., data) associated with the pixel or baseband video orimage information of the underlying information stream being processed.

The segmentation module 110 divides the encoded (or unencoded)information stream IN into a plurality of segments to produce asegmented information stream. The segmented information stream is thencoupled to compression 115A and, optionally, stored in a first providerstorage module 122. That is, the segmentation module 110 “chops” theinput information stream IN into a plurality of information segments ofthe same or different lengths according to one or more of a plurality ofcriteria. The criteria will be described in more detail below withrespect to FIG. 3.

In one embodiment of the invention, the segmentation module 110 mayarbitrarily “chop” the input information stream IN into segments of,e.g., 1000 packets up to an appropriate stream splicing exit point. Inanother embodiment of the invention, the segmentation module 110delineates a predefined, approximate number of frames (e.g.,approximately 100 or 1000 frames) within a video stream. The selectedsegment of frames includes those frames immediately preceding a scenecut (e.g., those frame immediately preceding an I-frame). In stillanother embodiment of the invention, the segmentation module 110 anapproximate number of video frames and associated audio frames areselected such that the segment thereby formed includes all the audioframes associated with the video segment (i.e., no audio frames in onesegment that are related to video frames in another segment).

It is desirable to avoid leaving “clues” to the scrambling process, suchthat a hacker might be able to piece together the various segments. Forexample, audio frames having known associations to video frames may beused to reconstruct the appropriate arrangement of the video frames.That is, discontinuities within the audio track (i.e., a break withinthe middle of a musical note or tone) may be matched together toreconstruct a video segment. Therefore, in one embodiment of theinvention the audio frames are segmented separately from the videoframes.

The segment size is determined with respect to the security leveldesired (i.e., more or smaller segments yields greater security), thestructure of the underlying information (i.e., fixed or variable groupof pictures, frequent video scene cuts and the like).

The compression module 115A compresses the segmented information streamaccording to, e.g., an MPEG or other compression scheme, depending uponthe type of information being distributed. For example, in the case ofthe input information stream in comprising a video information streamand associated audio information stream (e.g., a motion picture),compression module 115A may be used to encode the video informationaccording to an MPEG-2 compression technique, and the audio informationaccording to an AC-3 or other audio encoding technique. Compressionmodule 115A produces a compressed information stream that is coupled tore-sequencing module 130 and, optionally, stored in a second providerstorage module 124.

It should be noted that the order of segmentation module 110A and thecompression module 115A may be reversed. Thus, in FIG. 1, an alternateprocessing path for the input information stream IN is provided in whicha compression module 115B is used to process the input informationstream IN prior to segmentation by a segmentation module 110B.

Re-sequencing module 130 rearranges the compressed information segmentsaccording to a predetermined or pseudo-random pattern. That is,re-sequencing module 130 “shuffles” the compressed and segmentedinformation stream to produce a reordered or re-sequenced compressed andsegmented information stream and an associated index table indicative ofthe re-sequencing operation performed upon the compressed and segmentedinformation stream. The re-sequencing module 130 re-sequences theunderlying video and/or audio information according to one or more ofseveral criteria, such as scene boundaries, GOP size, temporal or framedisplacements, frame count, and the like. The re-sequenced compressedand segmented information stream is coupled to the information streamencryption module 135, while the associated index table is coupled tothe index table encryption module 140. Optionally, the output ofre-sequencing module 130 is coupled to third local storage module 126.

It is critical to the understanding of the present invention to notethat the purpose of the segmentation module 110A and the re-sequencingmodule 115A is to rearrange, in a seemingly random manner, e.g., thevideo and/or audio information associated with an underlying audio-videoinformation stream such that the presentation continuity of theunderlying audio-video information is destroyed. That is, thesegmentation module 110A and the re-sequencing module 115A remove thetemporal continuity of the underlying audio video information in amanner that renders the audio-video information unusable, or at leastunenjoyable, to a pirate or unauthorized subscriber.

The information stream encryption module 135 scrambles the re-sequencedcompressed and segmented information stream using one or more knownscrambling techniques. Additionally, the index table produced byre-sequencing module 130 is coupled to another encryption module 140,where it is encrypted in one of a number of known manners to produce anencrypted index table. The encrypted information stream (i.e., thescrambled re-sequenced, compressed and segmented information stream) andthe encrypted index table are coupled to information consumer orsubscriber side equipment via, e.g., distribution network 145 and/oralternate distribution network 145A.

The optional first 122, second 124 and third 126 local storage module126 are used to store, respectively, the output of segmentation module110A (or compression module 115B), the output of compression module 115A(or segmentation module 110B) and the output of re-sequencing module130. The local storage modules may be used to, e.g., store suchinformation for further processing by additional processing devices (notshown) or to allow processing of an entire information stream at eachstep (e.g., perform all segmentation of a received input informationstream IN, then perform all compression of the segmented informationstream, then perform all re-sequencing of the compressed and segmentedinformation stream, etc.). Optionally, the server side equipment may beused as a temporary buffer during a “one pass” processing of an inputinformation stream IN (such as a live broadcast of a baseball game).

Distribution network 145A and alternate distribution network 145B maycomprise any one of a number of standard distribution networks such as,microwave links, fiber optic networks, satellite links, cable televisionlinks, DVD, Internet, broadcast and the like.

In one embodiment of the invention an alternate distribution network145B is utilized to transport some of all of the scrambled sequencesproduced by encryption module 135. That is, the alternate distributionnetwork 145B may be used to transport, e.g., every fifth or some otherportion of the scrambled sequences produced by the encryption module135. In this manner, an unauthorized user intercepting the informationcarried by distribution network 145A would, even in the case of breakingthe various encrypt codes and properly re-sequencing the scrambledsegments, be unable to retrieve all of the scrambled sequences. Thus,alternate distribution network 145B provides an additional layer ofsecurity within the information distribution system 100 if FIG. 1.

The subscriber side equipment within the information distribution system100 of FIG. 1 comprises a local storage module 155, a decryption module150, a second decryption module 160, a random access module 165, adecompression module 170 and an optional pixel domain decoding module175.

The local storage module 155 receives the scrambled sequencestransported by distribution network 145A and/or 145B and stores thescrambled sequences. The first decryption module 150 is used to decryptthe encrypted index table transported by distribution network 145A toproduce a decrypted index table. The decrypted index table is coupled torandom access module 165. Second decryption module 160 accesses localstorage module 155 to retrieve scrambled sequences that are stored and,responsively, decrypt those scrambled sequences. The decrypted scrambledsequences (i.e., unscrambled sequences) are then coupled to randomaccess module 165. Random access module 165 utilizes the index tableinformation received from first decryption module 150 to rearrange thedescrambled sequences received from decryption module 160 to produce aproperly sequenced information stream at an output. That is, the outputof random access module 165 comprises an information stream having aplurality of segments that are arranged in a manner providing continuitywithin the underlying, illustratively, audio visual information stream.Decompression module 170 receives the information stream produced byrandom access module 165 comprising correctly arranged informationsegments and, responsively, decompresses the received information streamto produce one or more output information streams (i.e., an audioinformation stream, a video information stream and any ancillary datastreams). The output information stream OUT is optionally subjected topixel domain decoding module 175, where a pixel domain decode processthat is inverse of the pixel domain encoding process performed by pixelencoder 105 occurs.

FIG. 2 depicts a graphic representation of collection of informationsegments arranged in a non-standard (i.e., scrambled) order, and anindex table suitable for use in rearranging the collection ofinformation segments into a standard (i.e., unscrambled) order. In thegraphic representation of FIG. 2, the collection of information segmentsare stored in a memory such as local storage unit 155 of the system 100of FIG. 1, and the index table comprises a list of storage locationsfrom which to read, in order, to reconstruct the original order of theinformation segments. In this manner, improperly obtained distributeddata that is scrambled is not useful unless the index table is alsoobtained.

Specifically, FIG. 2 depicts an association between six locations (A-F)and six sequences (sequence 1-sequence 6). It should be noted that inFIG. 2 an oval indicative of a storage module is shown containing atable associating the locations and sequences. Specifically, location Ais associated with sequence 3, location B is associated with sequence 5,location C is associated with sequence 2, location D is associated withsequence 1, location E is associated with sequence 6 and location F isassociated with sequence 4. Thus, an index table comprising thefollowing sequence {D, C, A, F, B, E} indicates that the sequence isstored in memory should be retrieved, prior to being utilized, accordingto the associations described above to produce a properly sequencedinformation stream.

FIG. 3 depicts a flow routine of an information provider processingmethod according to the invention. The routine 300 depicted in FIG. 3 isdirected towards processing an audio video stream to produce asegmented, encoded, re-sequenced and encrypted audio and videoinformation stream and associated index information suitable forre-sequencing the segments.

The routine 300 is entered at step 302 and proceeds to step 304. At step304 an optional pixel domain encoding process is performed on the videoinformation within a received audio video information stream. Forexample, the pixel domain encoding process of step 304 may comprise awatermarking process, a pixel encryption process, a lip syncmodification process, an audio suppression process or a chroma strippingprocess. Watermarking involves the insertion of identifying an issuewithin video portion of an information stream such that copyright andother source indicative information may be included within a distributedinformation stream. Pixel encryption comprises any one of a number ofencryption techniques which render pixel information unusable withoutthe corresponding pixel decryption processing. Lip sync modificationcomprises a change in synchronization of the video and associated audioinformation based upon a random or predetermined temporal parameter suchthat video and audio are no longer synchronized, thereby severelydegrading the presentation of the audio video information stream. Audiosuppression comprises techniques for suppressing or otherwise hidingaudio information from a downstream audio decoder, such that the audioinformation may only be retrieved by a decoder cognizant of the newlocation or encoding technique used to hide the audio information.Chroma stripping comprises a process for removing or hiding chrominanceinformation from a downstream video decoder, such that the chrominanceinformation may be retrieved only by decoder cognizant of the locationor technique used to hide the chrominance information. The routine 300then proceeds to step 306.

At step 306 the audio video information stream is segmented into aplurality of contiguous information stream segments. These segments maybe determined with respect to scene cut indicia, temporal displacementparameters, frame counts, GOP structure and the like. The segments maybe of the same or substantially the same length or the segments may beof variable lengths. Each segment is associated with a segmentidentifier such that the original segment arrangement may be preservedby storing segment identifiers with a stream index table. The routine300 then proceeds to step 308.

At step 308 the segments are compressed according to, e.g., MPEG-2 videoand related audio compression techniques. Since the stream segmentsproduced at step 306 are typically self contained with respect to bufferbehavior, the compression processes utilized at step 308 may beperformed in parallel. That is, multiple audio visual stream segmentsmay be compressed in parallel using a parallel processing or parallelencoding technique. Otherwise, a single MPEG or other compression modulemay be used to process each stream segment in a standard manner toproduce a compressed output stream comprising a plurality of compressedstream segments. The routine 300 then proceeds to step 310. At step 310the compressed stream segments are re-sequenced (i.e., “shuffled”) toproduce a re-sequenced compressed audio video information stream andassociated index table. The index table includes information relatingthe re-sequenced segments to the initial sequence of segments such thatthe re-sequenced information stream segments may be rearranged toproduce the initial stream segment order. The routine 300 then proceedsto step 312.

At step 312 each of the re-sequenced information stream segments areencrypted to produce an information stream comprising a plurality ofencrypted, re-sequenced information stream segments. The routine 300then proceeds to step 314, where the index table used to maintaininter-segment associations is itself encrypted. The routine 300 thenproceeds to step 316. At step 316 the encrypted information streamsegments and the encrypted index table are distributed via, e.g., aninformation distribution network. The routine 300 then proceeds to step318 where it is exited.

FIG. 4 depicts a flow diagram of a subscriber side method for processingan information stream according to the invention. Specifically, theroutine 400 of FIG. 4 is directed towards processing a receivedencrypted index table and encrypted information segments to extract aproperly sequenced audio visual information stream for subsequentpresentation. The routine 400 is entered at step 402 and proceeds tostep 404.

At step 404 an encrypted index table received via a distribution networkis decrypted to provide a usable index table. The routine 400 thenproceeds to step 406, where a plurality of encrypted information streamsegments are decrypted to produce decrypted information stream segments.It must be noted that the decrypted information stream segments are notin a correct sequence with respect to the underlying audio visualinformation. That is, the decrypted information segments are “shuffled”such that presentation of the encrypted information stream segments(after, of course, decompression) would result in an undesirable choppy,temporally discontinuous audio visual presentation. The routine 400 thenproceeds to step 408.

At step 408 the decrypted information stream segments are accessedaccording to information within the decrypted index table. Specifically,the decrypted index table indicates a correct temporal order or sequencefor the decrypted information stream segments. Decrypted informationstream segments are retrieved from, e.g., a local storage module in acorrect temporal or sequential order as indicated by the decrypted indextable to produce a properly sequenced compressed information stream. Theroutine 400 then proceeds to step 410, where the properly sequencedcompressed information stream is decompressed to produce a decompressedaudio visual information stream. For example, the decompression processat step 410 is the inverse of the compression process used at step 308of the routine 300 of FIG. 3. The routine 400 then proceeds to step 412.

At step 412 an optional pixel domain decoding process is used to decodeany pixel domain encoding imparted to the information stream at step 304of the routine 300 of FIG. 3. The routine 400 then proceeds to step 414,where it is exited.

The above-described invention simultaneously provides for bothflexibility and security of electronically stored video information. Theessential observation is that, if compressed in an appropriate manner,video information that is stored on a random access storage device canbe re-sequenced with respect to its presentation flow. In normaloperation, compressed video typically cannot be chopped up and stored insegments, because the use of bi-directional motion prediction and theconstraints of neither overflowing nor underflowing rate buffersprohibit such operation. However, the MPEG-2 syntax does providemechanisms to treat portions of the video stream as self-containedentities. These mechanisms include the use of I and P frame GOPstructures (e.g., “IPPPPPPI . . . ”) or other “closed” GOP structures(e.g., “IBBPBBPI . . . ”) and the use of splice point syntax thatindicates periodic points at which buffers are filled to a known state.The invention provides an overall system that including both flexibilityand security.

It must be noted that if the segments are not self contained (e.g., nota closed GOP data structure), the VBV buffer status at the boundarieswould provide information to greatly assist in breaking the scramblingand reassembling of the proper video or audio sequence without thedecrypted index.

It is important to note that the invention addresses the securityweaknesses associated with continuity indicators, such as audiocontinuity, VBV buffer status, PTS and DTS information and the like.These continuity indicators are useful to those seeking to break thesecurity of the system and retrieve the “secured” data. By isolating orencapsulating such continuity indicators within a segment, and thenencoding the segment, the continuity indicators are not useful indecoding the segment.

FIG. 5 depicts a diagrammatic representation of the a layered securityenvironment enabled by the invention. Specifically, FIG. 5 depicts aseries of concentric circles representative of security layers. Thevarious layers of security have been described in detail above withrespect to FIGS. 1-4. FIG. 5 is useful in understanding the holistic,yet flexible approach to security that is enabled by the invention.

Specifically, a first layer of security is provided by a pixel domain orother baseband information domain (e.g., audio or data domain)processing layer 510. As previously discussed, the exemplary pixeldomain process may comprise, e.g., digital watermarking of videoinformation, insertion of copyright notices and other pixel domainsecurity measures. In the case of an information stream comprising anaudio information stream or other information stream, the pixel domainprocess will, of course, comprise an audio domain process or other datadomain process.

The security aspects of the pixel domain processing layer 510 areaugmented by a stream segmentation processing layer 520. The securityaspects of the stream segmentation processing layer 520 are augmented bya stream segment scrambling or re-sequencing layer 530. The securityaspects of the stream segment scrambling or re-sequencing layer 530 areaugmented by an encryption layer 540, including an optional indexencryption layer 535.

In addition to the above-described security layers 510-540, twoadditional optional security layers are provides. The first of theadditional optional layers comprises a multipath distribution layer 550,in which an information stream processed according to one or more ofprocessing steps 510 through 540 is transmitted or distributed to one ormore users via multiple signal paths. For example, the encrypted indexproduced at step 535 may be transmitted via a different signal path ormedium than the encrypted sequence of segmented or re-scrambledinformation frames produced at step 540.

The second of the additional optional layers comprises a temporalstaggering layer 560, in which portions of the information streamprocessed according to one or more of processing steps 510 through 540is transmitted to one or more information consumers in a temporarilynoncontiguous manner. That is, contiguous information stream segmentsare transmitted at different times (i.e., in temporally noncontiguousmanner) and temporally reassembled by the information consumer(s).

In the case of a single transmission channel, the temporal staggeringsecurity layer 560 cannot be used for real time distribution of secureinformation streams due to the inherent nature of temporal staggering(i.e., inherently not real time using a single channel). However,temporal staggering coupled with multipath distribution may be used todistribute real time information streams. For example, if three distinctcommunication channels are used to distribute encrypted informationsegments, then each of the three channels may be used to distributeencrypted information segments offset by three segments from theinformation segment previously transmitted on that channel. From theperspective of a single channel, each of the transmitted informationsegments is temporally offset from a preceding or following informationstream segment by the time normally associated with transmitting the twointervening information stream segments (i.e., the time normallyallocated to transmitting the two information stream segments carried bythe other two channels is not used by the one channel). Optionally, thisdead time may be filled with dummy information or information likely tocause errors or otherwise help thwart an unauthorized user.

In one embodiment of the invention, one or more information distributionchannels are used to transmit a plurality of segmented informationstreams. In this embodiment of the invention, the information segmentsassociated with each of the plurality of segmented information streamsare interleaved across the one or more information to be transmitted areinterleaved among one or more information distribution channels. Thesegmented information streams may optionally share encryption keys. Theinterleave method may be fixed or dynamic. In the case of a dynamicinterleave method, information suitable for reconstructing the variousinformation streams may be provided within one or more index tables.

While the amount of security afforded by an individual security layer isroughly represented by the relative position of the individual securitylayer, it must be noted that each layer addresses a different securitythreat. For example, the pixel domain (or, more generally, the basebandinformation domain) layer is addresses the identification and/or tracingof unauthorized information stream use and/or users. The segmentscrambling and encryption layers address the threat of hackers or otherunauthorized users gaining access to useful data within a receivedinformation stream. The multiple channel transmission and temporalstaggering layers address the physical avoidance of information streamreception by unauthorized users. The entire layered approach is directedtoward providing selective layers of security, depending upon, e.g., thesensitivity of the information to be distributed. For example, securingan electronic program guide may be deemed to be unnecessary. However,securing a first run movie distributed to theaters for subsequentpresentation is absolutely necessary.

Although various embodiments which incorporate the teachings of thepresent invention have been shown and described in detail herein, thoseskilled in the art can readily devise many other varied embodiments thatstill incorporate these teachings.

1. An apparatus for recovering image frames from an information stream,comprising: a memory for storing encrypted information stream segmentstransported by a distribution network; a recovering module forrecovering an index relating a second segment sequence to a firstsegment sequence; a decrypting module for decrypting the encryptedinformation stream segments to produce corresponding decryptedinformation stream segments; a re-sequencing module for re-sequencing,using said recovered index, said decrypted information stream segments;and a decompression module for decompressing, after said re-sequencingusing a prediction-based decompression process associated with saidcompression process, said compressed image frames included within saiddecrypted information stream segments.
 2. The apparatus of claim 1,wherein: said encrypted re-sequenced information stream is received viaa first medium; and said encrypted index is received via a secondmedium.
 3. The apparatus of claim 2, wherein said encrypted andre-sequenced information stream segments are received in a temporallydiscontinuous manner.
 4. The apparatus of claim 1, wherein saidre-sequencing module further comprises: an accessing module foraccessing, from a random access storage containing at least some of saiddecrypted information stream segments, said decrypted information streamsegments according to said first segment sequence.
 5. The apparatus ofclaim 1, wherein said re-sequencing module further comprises: anaccessing module for accessing, from a random access storage containingat least some of said encrypted information stream segments, saidencrypted information stream segments according to said first segmentsequence.
 6. An apparatus for recovering an information stream having afirst segment sequence from an encrypted re-sequenced information streamhaving a second segment sequence, comprising: a memory for storingencrypted information segments transported by a distribution network; arecovering module for recovering an index relating said second segmentsequence to said first segment sequence; a decrypting module fordecrypting said encrypted information segments to form respectivedecrypted information segments; a re-sequencing module forre-sequencing, using said recovered index, said decrypted informationsegments to form an information stream comprising a plurality of imagesegments arranged according to said first segment sequence; and adecompressing module for decompressing after said re-sequencing aplurality of image frames forming each of said information streamsegments by employing prediction-based decompression.
 7. Aprocessor-based method of providing an information stream comprising asequence of image frames to one or more consumers, comprising: receivingan encrypted re-sequenced information stream and an index, wherein theencrypted re-sequenced information stream and index are generated by:segmenting said information stream into a plurality of informationstream segments having a first segment sequence, each of saidinformation stream segments comprising a plurality of image frames;compressing said image frames after said segmenting step by employingprediction-based compression; re-sequencing said information streamsegments to produce a re-sequenced information stream having a secondsegment sequence, said first segment sequence being related to saidsecond segment sequence by an index; and encrypting said re-sequencedinformation stream and said index; and distributing said encryptedre-sequenced information stream and said index to one or moreinformation consumers.
 8. The method of claim 7, wherein, said step ofdistributing comprises the steps of: distributing, via a first medium,said encrypted re-sequenced information stream; and distributing, via asecond medium, said encrypted index.
 9. The method of claim 8, whereinsaid encrypted and re-sequenced information stream segments aredistributed to said one or more information consumers in a temporallydiscontinuous manner.
 10. The method of claim 9, wherein said encryptedand re-sequenced information stream segments are distributed to said oneor more information consumers in a temporally discontinuous manner. 11.The method of claim 10, wherein: said first medium comprises a pluralityof distribution channels, each of said plurality of distributionchannels distributing a respective plurality of said encrypted andre-sequenced information stream segments.
 12. The method of claim 7,wherein: each of said information stream segments comprises a firstnumber of compressed image frames.
 13. The method of claim 12, wherein:in the case of an information stream segment including one or morepredictively encoded compressed image frames, said one or morepredictively encoded compressed image frames being predictively encodedusing reference image frames within said information stream segmentincluding said one or more predictively encoded compressed image frames.14. The method of claim 7, wherein: a first compressed image framewithin each of said information stream segments comprises an intra codedframe.
 15. The method of claim 7, wherein: said information streamcomprises a plurality of image frames and associated audio frames; andeach of said information stream segments includes a respective firstplurality of image frames and a respective second plurality of audioframes, said first plurality of image frames and said second pluralityof audio frames intended for presentation during substantially the sametemporal period.
 16. The method of claim 7, wherein said informationstream comprises a plurality of image frames and associated audioframes, and wherein said step of segmenting comprises the steps of:segmenting said information stream into a plurality of image informationstream segments having said first segment sequence, each of said imageinformation stream segments comprising a plurality of image frames;segmenting said information stream into a plurality of audio informationstream segments having a third segment sequence, each of said audioinformation stream segments comprising a plurality of audio frames. 17.The method of claim 16, wherein said step of re-sequencing comprises thesteps of: re-sequencing said image information stream segments toproduce a re-sequenced image information stream having said secondsegment sequence, said first segment sequence being related to saidsecond segment sequence by said index; and re-sequencing said audioinformation stream segments to produce a re-sequenced audio informationstream having said fourth segment sequence, said third segment sequencebeing related to said fourth segment sequence by said index.
 18. Themethod of claim 17, wherein said image information stream and said audioinformation stream are encrypted using at least one of: a commonencryption technique using a common encryption key; different encryptionkeys using said common encryption technique; different encryptiontechniques using said common encryption key; and said differentencryption techniques using said different encryption keys.
 19. Themethod of claim 7, wherein said step of encrypting includes a step ofencrypting an indicia of buffer behavior.
 20. An apparatus comprising: asegmenting means for segmenting an information stream into a pluralityof information stream segments, said information stream segmentsarranged according to a first segment sequence, each of said informationstream segments comprising a plurality of image frames; a compressingmeans for compressing said image frames after said segmenting step byemploying prediction-based compression; a re-sequencing means for rearranging according to a second segment sequence, said informationstream segments including said compressed image frames, said firstsegment sequence being related to said second segment sequence by anindex; an encryption means for encrypting said re-sequenced informationstream segments and said index; and a storage means for storing saidre-sequenced information stream segments.
 21. The apparatus of claim 20,wherein: said index is distributed to one or more information consumersvia a first distribution channel; and said encrypted and re-sequencedinformation stream segments are distributed to said one or moreinformation consumers via a second distribution channel.
 22. Theapparatus of claim 21, wherein: said encrypted and re-sequencedinformation stream segments are distributed to said one or moreinformation consumers in a temporally discontinuous manner.
 23. Theapparatus of claim 21, wherein: said second distribution channelcomprises a plurality of distribution channels, each of said pluralityof distribution channels distributing a respective plurality of saidencrypted and re-sequenced information stream segments.